Safety control system for fluid fuel burners



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SAFETY CONTROL SYSTEM FOR FLUID FUEL BURNERS 5 Sheets-Sheet 2 Filed Aug. 9, 1946 JIVVENTOR. I/V/W/b'm 4 R y ATTORNEY Nov. Ti l- 11950 w. A. RAY 2,529,740

SAFETY CONTROL SYSTEM FOR FLUID FUEL BURNERS Filed Aug. 9, 1946 5 Sheets-Sheet 3 W7 0 1/ i a 7 .h AI? Z INVENTOR. VVM/[am 4. Pay

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SAFETY CONTROL SYSTEM FOR FLUID FUEL BURNERS Filed Aug. 9, 1946 s Sheets-Sheet 4 INVENTOR. VM/fiam A. Ray BY AT TORNE Y New M, 1950 w. A. RAY 2,529,140

SAFETY CONTROL SYSTEM FOR FLUID rum. BURNERS Filed Aug. 5, 1946 5 Sheets-Sheet 5 any.

FNVENTOR W/W/krm A Ra y BY 7-K 1 NTNEY Patented Nov. 14, 1950 SAFETY CONTROL SYSTEM FOR FLUID FUEL BURNERS William A. Ray, Los Angeles, Calif., assignmto General Controls 00., a corporation of California Application August 9, 1946, Serial No. 689,425

(Cl. l58117.1)

20 Claims.

This invention relates to a system for controlling the supply of fluid fuel to a burner, and particularly to such a system ensuring against escape of unignited fuel.

In an application filed in the name of William A. Ray on June 8, 1944, under Serial No. 539,377, entitled Fuel Supply System, now Patent No. 2,408,954, issued October 8, 1946, a fluid fuel con trol system is shown wherein the main control elements of the system are arranged to be energized, directly or indirectly, by a commercial source of electrical energy. Thus, upon failure of said source, the system is rendered inoperative, but the arrangement is such that mere resumption of the power supply suifices to return the system to operative condition.

Further, the system is arranged to ensure automatic interruption of the fuel supply upon failure of the pilot flame. For this purpose, a phototube of the electron multiplier type is provided, which tube is connected to be energized by the commercial source, the photocathode being illuminated by the pilot flame. Upon extinguishq ment of the pilot burner, the system can be returned to operation only by a manual valve resetting operation and reignition of the pilot flame. A

It is an object of this invention to provide an improved system of this character.

It is another object of this invention to provide such a system which does not require a manual valve resetting operation to restore the system to operative condition.

It is another object of this invention to provide such a system in which the phototube furnishes rectified current for operating the pilot burner valve, a supplemental source of rectified current being provided for the main burner valve.

It is still another object of this invention to provide such a system having supplemental means responsive to the condition of the pilot burner valve for controlling the operation of the main valve.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several embodiments of the invention. For this purpose there are shown a few forms in the drawings accompanying and forming part of the present specification. The forms will now be described in detail illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken 2 in a. limiting sense, since the scope of this invention is best defined by the appended claims.

Figure 1 is a schematic diagram of a system incorporating the invention;

Fig. 2 is a plan view of a valve structure adapted for use in the system of Fig. 1;

Figs. 3 and 4 are sections taken as indicated by the correspondingly numbered lines on Fig. 2;

Figs. 5 and 6 are fragmentary sections, taken as indicated by the correspondingly numbered lines on Fig. 3;

Fig. '7 is a diagrammatic view taken as indicated by the lines 1-! of Fig. 3;

Figs. 8 and 9 are diagrams similar to Fig. 7, showing diiferent operating positions of the valve closure; I

Figs. 7a, 8a, and 9a are diagrams illustrating various positions of the main valve closure corresponding to section line Ia-la of Fig. 3;

Fig. 10 is a graph, useful in explaining the control functions of the valve of Fig. 2;

Fig. 11 is a transverse section of a valve which may be used for automatically controlling the main burner;

Fig. 12 is a diagram similar to Fig. 1, showing a modified form of system; and

Fig. 13 is a view similar to Fig. 3 showing a modified form of valve adapted for use in the system of Fig. 12.

The system of the invention may be used for the control of liquid or gaseous fuels. Referring to Fig. l, a system adapted for gaseous fuel is shown, having a main burner I supplied with fuel from an appropriate source by a pipe 2 controlled by a main valve .3 and a combination valve structure 4. The combination valve structure 4 supplementarily controls a conduit 5 for passing fuel to the pilot burner 6, which provides normally, a continuously burning flame 1 for igniting the main burner I when valves 3 and 4 are operated to pass fuel thereto. For this purpose the conduit 5 is connected to the fuel supply, so as to be independent of the valve 3, as by being connected to the conduit 2 between the source and the valve 3. In this way closing of the valve 3 has no eiiect on the fuel supply to the pilot burner 6. The main valve 3 is electrically operated, and the valve structure 4 includes a pilot burner valve 2|, also electrically operated for -controlling the fuel supply to the pilot burner 6.

Control circuits are provided respectively for the valves 3 and 2|, which are responsive to the existence of the pilot flame I. For this purpose these circuits include a light sensitive device, such as a phototube 9, arranged to respond solely to the light of the pilot flame 1. Light from 'other sources, including the main burner I, may

be excluded by suitable shields, or by appropriate location of the tube 9.

A focusing device l may be used to concentrate the light from the flame I onto the light sensitive element of the tube 9.

The circuit for the main valve 3 includes a condition responsive switch mechanism II, which may be, for example, a conventional thermostat, responding to the temperature of a space to be heated by the burner If the pilot flame 1 fails, the main valve 3, if open, closes immediately, and the pilot burner valve 2| also closes, assuming there has been no failure of the commercial current source. The combination valve 4 includes means for by-passing the pilot valve 2| to permit the pilot flame I to be re-established.

Upon re-establishment of the pilot flame 1, the pilot valve 2| opens and the main valve 3 may or may not open, as required by the condition responsive means I The combination valve 4 ensures against passage of fuel to the main burner until after the operation of lighting the pilot burner has been completed. This ensures the operator against possible injury by the substantially coincident ignition of the main burner and the pilot burner, which would occur it the means I I were calling for heat at this time.

In the event of power failure, the main valve 3, if open, closes at once. The pilot burner valve 2|, however, is arranged to remain open. In this way, the need of servicing each and every valve, such as 2|, in the district where a power failure has occurred is avoided.

The combination valve 4 is shown in detail in Figs. 2 to 6 inclusive, and comprises a manually operable valve structure and an electro-magnetic valve structure, indicated generally by the numerals and 2| in Fig. 2, the vertical arrows indicating the direction of flow through valve 28 and the horizontal arrows indicating the direction of flow through valve 2|.

The valve structure 20 comprises a casing 22 having a tapered seat for a rotatable tapered plug 23, which is maintained seated by means 01' a spring 24 compressed between the bottom of the plug and a plate 25 covering the open :bottom end of the casing. A main opening 26 extends diametrically through the lower portion of the plug 23 and is adapted, upon 90 rotation from the position of Figs. 3 and 4, to establish 4| extend outwardly and upwardly from the mouth of the cup 40, as best shown in Fig. 6, the extension 39 being omitted for the sake of clarity.

A sleeve 42 is disposed about the extension 38, and has a flared bottom end to which a ball-race 43 is secured, as by welding. Balls 44, interposed between the race 43 and the top surface oi casing 22 about the extension 39, provide a ball bearing support for the sleeve 42. The sleeve 42 is held in place on the extension 39 by a snap ring 45 which engages a shoulder on the extension.

A lost motion connection is provided between the sleeve 42 and the cup, or plug operating member 40, extending diametrically across the sleeve 42, the extremities of the arm 46 being received in conforming slots in the sleeve 42. The intermediate portions of the arm lie between the fingers 4| of the member 40 (see Fig. 6). A handle 48, having a cupped portion 48a fitting over the sleeve 42, is secured to the arm 46 as by a screw 41. The cupped portion 48a has a pair of projections providing opposed recesses 49 for receiving respectively the opposite ends of the arm 46, an additional recess 4911 being provided to permit attachment of the handle 48 at a position 90 from that shown, if desired.

A lug 50 projects from the ball-race 43, and is adapted to cooperate with a lever 5| pivoted in a recess 50a in the casing 22 (see Fig. 5) and engaging the upper end of the pin 31. It will be apparent that the plug 23 can be rotated by manipulation of the handle 48; and, if the handle 48 is turned clockwise through a small angle from the full line position, as shown in Fig. 6,

- the valve ball 33 will be unseated. When the communication between the inlet and outlet openings 21 and 28 (Fig. 4). A groove 29 in the surface of the upper portion of the plug 23 serves to establish communication between the inlet and outlet passages 38 and 3| (Fig. 3).

. The side wall of casing 22 has a vertical bore 32 leading downwardly from the outlet passage 3|. The bore 32 is restricted, near its upper end, to form a downwardly facing seat for a valve ball 33, controlling communication between the passage 3l, and another passage 36 leading from the bore 32. The valve ball 33 is urged to seat by a compression spring 34 confined between the ball 33 and an adjusting screw 35 threaded in the lower end of the bore 32. An actuating pin 31, closely guided in a relatively long opening through the top wall of the casing 22, rests on the ball 33.

The flattened stem 38 of the plug 23 extends into a tubular extension 39 formed on the top wall oi. the casing 22. Within this extension 39 is a cupped member 48 having its bottom wall apertured to flt the stem 38. Four spaced fingers handle 48 is released, the spring 34 will seat the ball 33 and return the handle 48 to its full line position, due to the lost motion connection between the arm 46 and the fingers 4|, and also due to the anti-friction mounting of the handle assembly.

The groove 29 extends only part way around the plug 23 and, as shown in Fig. 7, its angular relation to the plug passage 26 is such that, when the plug passage 26 extends transversely between the inlet and outlet 21 and 28 (Fig. 7a) so as to interrupt communication therebetween, communication between passages 38 and 3| also is interrupted. When the plug 23 is turned clockwise through an angle of to the position of Fig. 8a, communication is established between passages 21 and 28, and between passages 38 and 3| (Fig. 8). When the plug 23 is rotated through an additional angle of 90 to the position of Fig. 9a, corresponding to that of Figs. 3 and 4, fluid can still pass between passages 30 and 3| (Fig. 9), but the main flow between inlet and outlet 21 and 28 is obstructed. When the plug is rotated through an additional small angle to unseat the valve ball 33, the conditions are as indicated by the broken lines in Fig. 9a, passages 38 and 3| still being in communication, while flow between passages 2'! and 28 isstill obstructed.

These various conditions of the valve plug 23 are illustrated graphically in Fig. 10, wherein the heavy lines bearing the legends "Main Valve On" and "Pilot Valve On respectively indicate flow between the inlet 21 and the outlet 28, and from passage 30 to passage 3|, while the legend "By- Pass Open" refers to the unseated condition of the valve ball 33. The straight dot-dash lines in Fig. 10 numbered 1, 8 and 9 correspond to the plug positions illustrated in the correspondingly numbered figures of the drawing; also, these lines correspond to the broken and solid line positions of the handle 99, as shown in Fig. 6. The dotdash line to the right of line 9 corresponds to the position of the handle 99 when it is moved through a slight angle in the clockwise direction from the full-line position of Fig. 6 for opening the bypass 9I.

The electromagnetic valve 2| (Fig. 3) comprises a casing 92 secured to the casing 22 of the plug valve 26 by screws '99 (Fig. 2) enga ing flanged portions of the casings. An inlet passage 69, in register with passage 9|, is provided in the casing 62. a branch passage 66 leading from passage 69 to a valve chamber 66 formed above the casing. A disc-shaped closure 61 of magnetizable material is accommodated in the chamber 69, and normally is supported at three points, viz., a valve seat 99 surrounding the outlet port 59, and a pair of pins one of which is shown at 96. By such an arrangement, generally disclosed in Patent No. 2,294,421 of September 1, 1942, only a small amount of power is required to effect an initial tilting of the closure 51 on its seat 66. the resultant relief of fluid pressure in the chamber 69 facilitating movement of the closure 61 to its fully open position. The port 59 leads/to an outlet passage 6| which also is in communication with the passage 96 of plug valve 26.

On top of the casing 52 is an electromagnet structure, comprising an inverted cup-shaped magnetic shell 92 to which is welded a flanged supporting ring 69 (see also Fig. 2), secured to the casing 52 in a fluid-tight manner by screws passing through the flange and threaded into the casing. A central core 69 is secured to the shell 62, as by a threaded extension 69a extending through the top wall of the shell, and carrying a nut 69b engaging this wall. The core 99 has a tapered enlargement 65 providing a large surface in intimate contact between the core and the shell. The lower end of the "core 69 is formed to provide a polar enlargement 99, the face of which is in the plane of the pole face formed by the underside of the inwardly turned.

filed May 11, 1946. Furthermore, a valve operated by an electromagnet of this type has important advantages, among .which is the capability of successful operation by a weak current.

Such a valve is further disclosed and claimed in a copending application, Serial No. 671,583 flled May 22, 1946, in the name of William'A. Ray.

In the system of Fig. 1, the combination valve 9 corresponds to the valve structure of Figs. 2-5, just described, the parts thereof being designated in Fig, 1 by the same reference numerals, the

part indicated by 3311 representing the complete fuel to the main burner I when thevalve 9 is' an inlet III and an outlet I62. A ported wall I99 is provided between the inlet and the outlet and carries a valve seat I94 with which a disc-like closure member I66 of magnetiza-ble material cooperates to control fluid flow through the body I69. On top of the body I66 is an electromagnet structure comprising an inverted cup-shaped mag.

valve constituted by the ball- 99. The other parts netic shell I66 to which is welded a flanged supporting ring I61 secured to the body I69 in a fluidtight manner by screws I99 passing through the flange and threadedly engaging the body. A central core I69 has a tapered circular head II9 secured in a corresponding recess III provided in the top wall of the shell I96, by means of a nut II2, engaging a threaded extension II9 of the core which passes through the said top wall.

The lower end of the core I99 is formed with a polar enlargement II9, having its face in the plane of the pole face formed by the underside of the inwardly turned flange I I5 of the shell I69. A winding IIS on the core I69 serves to energize the core I69 in response to passage of current, and causes the core I99 to raise the closure I69 from seat I69 against the force of spring Ill-to permit fluid through the valve. This winding H6 is a direct current winding. Upon cessation of the current in winding Hi, the closure I69 is at once released and returnsto closed position in response to the spring I I1. The large polar areas and small air gap providedby the'valve ensure its successful operation by a very'small current.

The pilot burner conduit 6 (Figs. 1 and 3) leads from the main-conduit 2 to the inlet passage 99 of the upper section of the plug valve 29, the outlet passage 9 I being connected directly to the inlet 69 of the electromagnetic valve 2i. A continuation 6a of the pilot burner conduit leads-to the pilot burner 9 from the outlet passage II of the valve 2I.

In the present instance, a phototube 9 is-arranged to respond to the existence of the pilot flame 1 to supply current for operating the electromagnetic valve 2 I This tube 9 serves not'only as a control for the valve, but additionaliyto supply unidirectional current for the winding-99. This current is pulsating; and, accordingly a conliitllagnse: 269 may be connected across the wind- To ensure sufficient current for operating the valve 2I in response to the slight illumination provided by the pilot flame 1, the phototube' 9 is of the electron multiplier type. such, for example, as that type known commercially as the 931a. The tube 9 includes a photo-sensitive cathode I 26 which emits electrons when its activesurface-is illuminated, as by the flame 1. The anode I21 finally receives the electrons produced in the tube by successive action of the electrons upon a number of secondary emitters, or auxiliary electrodes, I22, I29, I29, I26, I29, I21, I29, I29, and I96, subjected to ,successively increased potential by being connected to taps on the secondary winding III of a step-up transformer I92. The primary winding I99 may be connected to a commercial alternating current source. The operation of such a tube is well known and will not be dis- 76 cussed here.

winding 03, the other terminal being joined by a conductor I35 to the upper terminal of the secondary I3I. The circuit includes section 202, conductor I48, and auxiliary anode I30. A winding I52 is included in conductor I34 for providing an electric interlock system which will be described in detail hereinafter.

This circuit and coil 68 are energized, maintaining the valve 2I open, as long as the cathode I is illuminated by the pilot flame 1. Upon failure of the pilot flame I, and assuming there has been no failure of the commercial power supply, the valve 2I closes and, upon reestablishment of the pilot flame, the valve 2| reopens. However, the arrangement is such that, upon failure of the power supply, the valve 2| remains open. For this purpose the supplemental winding 55 is provided on the core 54, and is connected to the alternating current source, as by being connected in series with the transformer primary I33.

The winding 69 is arranged to produce a magnetomotive force which is Just sufficient to neutralize the magnetic remanence of core 54 when the winding 50 is de-energized. By appropriate design and choice of material for the core 04, this remanence is such as to retain the valve closure or armature 51 of valve 2I in attracted position, even when the winding 68 is de-energized. Accordingly, for the closure 51 to be released, the winding 58 must be energized to neutralize the remanence. A system arranged to maintain the pilot burner valve open in this way upon power failure is disclosed in a copending application, Serial No. 539,377, filed June 8, 1944, in the name of William A. Ray, now become Patent No. 2,408,954, granted October 8, 1946.

Winding II5 for operating the valve 3 is energized by rectified alternating current that is rendered effective only while the pilot light I is in existence, and phototube 9 is active. This is effected by the aid of the electronic emission device or audion I 40. This device has an anode I and a cathode I43 provided with a heater I44. This heater is energized from a secondary winding I45 forming a part of the transformer I32. The automatic switch mechanism II, such as a thermostat, is connected in series with the heater I44. In this way, it is only when the automatic switch mechanism demands more heat that the heater I44 is energized.

The device I40 also includes the control or grid electrode I42.

Any two adjacent sections of the secondary I3I, such as the sections 202 and 203, may be used for providing the required potential differences for the electrodes of the device I40. Thus, for example, the lower terminal of section 203 is connected to the control electrode I42 through a winding I5I of transformer I 50, and a conductor I53. The cathode I43 is connected to the junction I43 between these two sections by the aid of the conductor I40. The anode I is connected through a conductor I46, winding H5, and conductors I41 and I to the upper terminal of section 202. Since the current supplied to winding III is pulsating, a condenser 20I may be connected across the winding.

First, assuming that the transformer I50 is inactive, no current can flow through winding 8 H5. This is apparent from the following considerations. Thus, when the upper terminal of section 202 is positive as the current alternates through the secondary winding I3I, the grid or control electrode I42 is then negative with respect to the cathode I43, and, accordingly, the space current is reduced to zero. On the other hand, when the upper terminal of section 202 is negative, then the anode I 4| is likewise negative with respect to the cathode I43 and, again, no space current can flow.

However, when there is a flame I at the pilot burner 6 a pulsating current flows through the winding I52 of transformer I50, since this coil I52 is in series with the phototube 9. Accordingly, this pulsating current sets up alternately negative and positive potentials on grid I42. The connection is such that, when the anode I is positive, the grid I42 becomes positive, and then space current is permitted to flow in the audion I40. The winding H5 is then energized by a pulsating current. It is apparent that energization of winding IIG depends upon illumination of the cathode I20 of the phototube 5. Accordingly, the energization of winding IIG depends upon two factors: the condition of automatic switch II and the condition of the phototube 3.

In the event of power failure, the coil 53 is not energized, and therefore the remanence of core 04 retains the closure 51 in attracted position, assuming the closure already was in that position. On the other hand, the main valve 3 closes, since the winding H5 is de-energized.

Normally without power failure, the pilot burner valve M is maintained open only while the pilot flame I is in existence. Upon extinguishment of the flame I, the phototube 9 becomes inactive. This causes the tube I40 to become nonconducting, de-energizing coil H5 and causing the main valve 3 to close. At the same time, coil 50 is de-energized, and, since coil 00 neutralizes the magnetic remanence in core 64, valve 2I also closes.

In Fig. 1, the plug valve 20 is in the condition shown in Figs. 2-6 and 9, the handle lug 50 being adjacent the pin 31. Since the pilot flame I is burning, coil 63 is energized and valve 2I is open. The main valve 3 may be either open or closed. depending on the requirements of the automatic switch II. However, no fuel can pass at this time to the main burner I, since the plug passage 26 is in flow-preventing position. To establish normal operation of the system, the valve plug 23 is turned counterclockwise through to the open position of Fig. 8a. The main valve 3 then automatically controls fuel flow to the main burner I in accordance with the requirements of the automatic switch I I. If it is desired completely to discontinue operation of the system. plug 23 is turned to the position of Fig. 7a so that flow through both sections of the valve 20 is prevented. Due to the extinguishment of the pilot flame I, the phototube 9 is no longer capable of passing current and the valves 3 and 2I accordingly both close, ensuring positive shut-off of the fuel.

If the pilot flame I is extinguished during normal operation of the system with the plug 23 in the position of Fig. 8a, the valves 3 and 2I both close as previously described. To light the pilot burner 8 and thereby restore the system to operation, the plug 23 is rotated to the position of Fig. 9a, and slightly beyond, to cause the handle lug 50 to open the by-pass valve 33a.

.. Fuel flow to the main burner I is obstructed at venting position indicated by the broken lines in Fig. 9a, and also by the main valve 3 which is closed due to the fact that the winding H8 is not energized.

Upon ignition of the pilot flame, the phototube .8 passes current to energize coil 88 and causes the pilot valve 2| to open, this opening being evidenced by an audible click. Thereupon, the plug valve handle 48 is released and returns under the force of the bias spring of valve 88' to the solid line position of Fig. 6. This allows valve 88a to close and places control of the fuel flow to the pilot burner 6 under the valve II. If normal operation of the system is then desired, the plug 28 is rotated back to the position of A system having a slightly different mode of operation, and employing for this purpose a modified form of combination valve, is shown in Fig.12, the valve being shown in Fig. 13. Reierring to Fig. 13, the modified combination valve comprises a plug valve 20 identical with that employed in the previouslydescribed valve of Figs. 2-6, and an electromagnetic valve 83 similar to valve it except that the outlet passage is enlarged to provide a chamber 84, the bottom wall of which is formed by a flexible diaphragm 85. This diaphragm 85 is clamped at its margin to the valve casing by a switching device generally indicated by $8.

Inasmuch as this switching device 88 is of conventional. construction and forms, per se, no part of the present invention, it suflices to state that, when the actuating button 81 is moved downwardly by gas pressure in chamber 8| act ing on the diaphragm 85, a bridging element 88 is brought into engagement with; contacts 88,

and 3B and, when the pressure is released, a

reverse action occurs.

Referring to Fig. 12, the system is quite similar to the system of Fig. 1, comprising a main burner i, the supply of fuel to which is controlled by the plug valve 20 and an electromagnetic valve 3 with an operating winding 6. The name ll of the pilot burner} serves to illumihate the cathode 520 of the phototube 9 to cause the tube a to pass current, the winding 68 of the pilot burner valve 83 being connected between the anode l2! and the anode I88 so as to he energized and de-energized in accordance with the existence or non-existence of the pilot flame, and thus operate the valve 83.

In this form of the invention, the circuit for energizing the main valve'winding H8 includes a conventional rectifier 860, which may be a tube or oxide type energized by the transformer 10 switch 88 closed. Thus. the coil 8 is energized and de-energ'ized in accordance with the dictates of the automatic switch II to cause the main valve 8 to open and close.

secondary H5 and controlled by the automatic switch M, and the switch 86 operated in response to passage of fuel to the pilot burner 6. Thus, a conductor Q88 leads from the lower terminal of the secondary M5 to one terminal of the winding iii; a conductor I62 leads from the other terminal of winding I Hi to one of the switch contacts as 89; a conductor 863 leading from the other contact 90 to the upper terminal of the secondary 5 through the rectifier I80 and the automatic switch ll.

With the plug 23 of valve 20 positioned to pass fuel to the main burner I and to the pilot burner B, and with the pilot flame 1 burning, the phototube 8' delivers unidirectional current to winding 58, maintaining the pilot valve 83 in open position, the pressure of the fuel passing to the pilot burner through chamber 84 maintaining the Upon extinguishment of the pilot flame 1, the phototube 8 ceases to deliver current to the winding 88, thus causing the pilot valve 88 to close and relieving the fluid pressure in the chamber 84. This, in turn, allows the switch 86 to open. so that the main valve 8, if open, is caused to close or is prevented from opening.

The system of Fig. 12 is restored to normal operation in the same manner as that of Fig. 1; that is, the handle 48 of the plug valve 20 is operated to position the plug 23 to prevent passage of fuel to the main burner l, and to cause the valve 38a to by-pass valve 88 and pass fuel to the pilot burner 6. Upon establishment of the flame I, the phototube 9 energizes the coil 68, which opens the valve 88 with the previously mentioned click. Thereafter the plug 28 is returned to fuel passing position and the control of the main burner I restored to the main valve 3 and the automatic switch il.

As before, the pilot valve 88 is arranged to be held open by the magnetic remanence in core 64, unless the remanence is neutralized by current flow from the power source in the winding 69. Thus, upon power failure, the pilot valve 83 remains open regardless of the pilot flame l, but the main valve 3 is caused to close or to remain closed, since there is no current flow in the trans former secondary H5.

The inventor claims:

1. In a fluid fuel control system: a main burner; an electrically operated main valve for controlling fuel flow to the main burner; a pilot burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner; a photoelectric tube having a photo-sensitive cathode and adapted to be energized by an alternating current supply for rectifying the alternating current and supplying unidirectional current for operating said pilot burner valve, the flame of the pilot burner activating said cathode; supplementary means for supplying current to operate the main valve; and control means energizable by the current operating the pilot burner valve, and when energized to control said supplementary means to pass current to operate said main valve.

2. In a fluid fuel control system: a main burner; an electrically operated main valve for controlling fuel flow to the main burner; a pilot burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner; means responsive to the existence of a pilot flame for supplying current to operate said pilot burner valve; means for supplying current to operate the main valve; and means responsive to the current supply to the pilot burner valve for controlling operation of the main valve.

3. In a fluid fuel control system: a main burner; a pilot burner for producing a pilot flame; an electrically operated main valve for controlling fuel flow to the main burner; an electrically oper ated pilot burner valve for controlling fuel flow to the pilot burner, having a magnetic member and a winding for magnetizing said member; an electronic emission device energizable from a source of alternating current, said device serving to rectify the alternating current, and supplying the resultant unidirectional current to said winding for holding the pilot burner valve open only while the pilot flame is in existence, the remanence of said magnetic member being suflicient to maintain said pilot burner valve open after said winding is deenergized; a demagnetizing winding for the magnetic member, energized from said alternating current source, said demagnetizing winding operating to render said remanence ineffective while the source of alternating current is active; means for supplying current to operate the main valve; and control means energizable by the current from said electronic emission device and when energized, to control said current supply means to pass current to said main valve.

4. In a fluid fuel control system: a main burner; a pilot burner for producing a pilot flame; an electrically operated main valve for controlling fuel flow to the main burner; an electrically operated pilot burner valve for con trolling fuel flow to the pilot burner, having a magnetic member and a winding for magnetizing said member; an electronic emission device energizable from a source of alternating current, said device serving to rectify the alternating current and supplying the resultant unidirectional current to said winding for holding the pilot burner valve open only while the pilot flame is in existence, the remanence of said magnetic member being sufllcient to maintain said pilot burner valve open after said winding is deenergized; a demagnetizing winding for the magnetic member, energized from said alternating current source, said demagnetizing winding operating to render said remanence ineffective while the source of alternating current is active; supplemental means energizable from said source of alternating current, said means serving to rectify said alternating current and supplying the resultant unidirectional current to operate the main valve; and control means energizable by the current from said electronic emission device and when energized, to control said supplemental means to pass current to said main valve.

5. In a fluid fuel control system: a main burner; a pilot burner for producing a pilot flame; an electrically operated main valve for controlling fuel flow to the main burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner, having a magnetic member and a winding for magnetizing said member; a. photo-electric tube having a photo-sensitive cathode affected by the pilot flame, said tube being energizable from a source of alternating current, said'tube serving to rectify the alternating current and supplying the resultant unidirectional current to said winding for holding the pilot burner valve open only while the pilot flame is in existence, the remanence of said magnetic member being suflicient to maintain said pilot burner valve open after said windin is deenergized; a demagnetizing winding for the magnetic member, energized from said alternating current source, said demagnetizing winding operating to render said remanence ineffective while the source of alternating current is active; means for supplying current to operate the main valve; and control means energizable by the current from said tube, and when energized, to control said current supply means to pass current to said main valve.

6. In a fluid fuel control system: a main burner; a pilot burner for producing a pilot flame; an electrically operated main valve for controllin fuel flow to the main burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner, having a magnetic member and a winding for magnetizing said member; an electronic emission device ener- 12 gizable from a source of alternating current, said device serving to rectify the alternating current and supplying the resultant unidirectional current to said winding for holding the pilot burner valve open only while the pilot flame is in exist ence, the remanence of said magnetic member being sufllcient to maintain said pilot burner valve open after said winding is deenergized; a

- demagnetizing winding for the magnetic memher, energized from said alternating current source, said demagnetizing winding operating to render said remanence ineffective while the source of alternating current is active; means for supplying current to operate the main valve; control means energizable by the current from said electronic emission device and when energized, to control said current supply means to pass current to said main valve, and condition responsive means cooperating with said control means also to control said current supply means.

7. In a fluid fuel control system: a main burner; a pilot burner for producing a pilot flame; an electrically operated main valve for controlling fuel flow to the main burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner, having a magnetic member and a winding for magnetizing said member; a photo-electric tube having a photo-sensitive cathode affected by the pilot flame, said tube being energizable from a source of alternating current, said tube serving to rectify the alternating current and supplying the resultant unidirectional current to said winding for holding the pilot burner valve open only while the pilot flame is in existence, the remanence of said magnetic member being sufllcient to maintain said pilot burner valve open after said winding is deenergized; a demagnetizing winding for the magnetic member, energized from said alternating current source, said demagnetizing winding operating to render said remanence ineflective while the source of alternating current is active; means for supplying current to operate the main valve; control means energizable by the current from said tube, and when energized, to control said current supply means to pass current to said main valve, and condition responsive means cooperating with said control means also to control said current supply means.

8. In a fluid fuel control system: a main burner; an electrically operated main valve for controlling fuel flow to the main burner; a pilot burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner; a normally closed bypass valve for passing fuel to the pilot burner and independently of the electromagnetically operated pilot burner valve; means for temporarily opening said bypass valve; means responsive to the existence of a pilot flame for supplying current to operate the pilot burner valve; a grid controlled rectifler connected to a source of alternating current for supplying unidirectional current to operate the main valve; means for applying a biasing potential on said grid from said source to prevent current flow through the rectifier; and means including a pair of inductively coupled coils and responsive to current flow to the pilot burner valve for altering said biasing potential to control said rectifier to pass current.

9. In a fluid fuel control system: a main burner; an electrically operated main valve for controlling fuel flow to the main burner; a pilot burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner;

switch means operated in response to the pressure of the fuel flowing to the pilot burner; means responsive to the existence of a pilot flame for supplying current to operate the pilot burner valve; manually operable means optionally to by-pass said pilot burner valve, and circuit forming means, including said switch means, for operating the main valve to open in response to fuel flow to the pilot burner.

10. In a fluid fuel control system: a main burner; an electrically operated main valve for controlling fuel flow to the main burner; a pilot burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner; a normally closed bypass valve for passing fuel to the pilot burner and independently of the electromagnetically operated pilot burner valve; means for temporarily opening said bypass valve; means responsive to the existence of a pilot flame for supplying current to operate the pilot burner valve; a grid controlled rectifier connected to a source of alternating current for supplying unidirectional current to operate the main valve; means controlling said source for applying a biasing potential on said grid to prevent current flow through the rectifier; means including a pair of inductively coupled coils and responsive to current flow to the pilot burner valve for altering said biasing potential to control said rectifier to pass current, and condition responsive means for supplementarily controlling said rectifier.

ii. In a fluid fuel control system: a main burner; an electrically operated main valve for controlling fuel flow to the main burner; a pilot burner; an electrically operated pilot burner valve for controlling fuel flow to the pilot burner; switch means operated in response to fuel flow to the pilot burner; means responsive to the existence of a pilot flame for supplying current to operate the pilot burner valve, manually operable means optionally to by-pass said pilot burner valve; circuit forming means. including said switch means, for operating the main valve to open in response to fuel flow to the pilot burner, and condition responsive means cooperating with said switch means to control the operation of the main burner.

12. In a. fluid fuel control system: a main burner; a pilot burner for providing a pilot flame; a main burner valve and a pilot burner valve for respectively controlling fuel flow to said burners, each of said valves being electrically operated; a photo-electric tube having a photosensitive cathode and energizable from a source of alternating current, said tube serving to rectify the alternating current and supply the resultant unidirectional current to operate the pilot valve, said pilot flame activating the cathode for controlling the flow of said unidirectional current; manually operable means optionally to bypass said pilot burner valve; means forming a supplementary source of unidirectional current for operating the main valve; and control means operated by current from said tube for controlling said supplementary source to supply current to operate the main valve.

13. In a fluid fuel control system: a main burner; a pilot burner; an electromagnetically operated valve for supplying fuel to the pilot burner; means providing a passage of fuel to said pilot burner independently of said valve; means responsive to the igniting of the pilot burner for energizing said electromagnetically operated valve to cause the valve to open; said valve being capable of remaining open due to magnetic rem- 14 anence; and alternating current means for substantially neutralizing said remanence.

14. In a fluid fuel control system: a main burner; a pilot burner; an electromagnetically operated valve for supplying fuel to the pilot burner; means providing a passage of fuel to said pilot burner independently of said valve; means responsive to the igniting of the pilot burner for energizing said electromagnetlcally operated valve to cause the valve to open; said means including a source of alternating current and a rectifier; said valve being capable of remaining open due to magnetic remanence; and means operated from said source for substantially neutralizing said remanence.

15. In a fluid fuel control system: a main burner; a pilot burner; an electrically energlzable valve mechanism for the main burner; and means for operating said valve mechanism comprising an electronic emission device having a cathode, a control electrode and an anode, said control electrode and anode being connectible across a source of alternating current, and thecathode being connectible to the source to impress a potential on the cathode of a valve intermediate the potentials of the control electrode and anode; and means responsive to the existence of the pilot flame for supplementarily affecting the potential of the control electrode to provide a positive potential for said control electrode, the valve mechanism being energizable to open it by aid of current through said device.

16. In a fluid fuel control system: a main burner; a pilot burner; an electrically energisable valve mechanism for the main burner; and means for operating said valve mechanism comprising an electronic emission device having a cathode, a control electrode and an anode, said control electrode and anode being connectible across a source of alternating current, and the cathode being connectible to the source to impress a potential on the cathode of a valve intermediate the potentials of the control electrode and anode; means responsive to the existence of the pilot flame for supplementarily affecting the potential of the control electrode to provide a positive potential for said control electrode, the valve mechanism being energizable to open it by aid of current through said device; and condition responsive means for activating said cathode.

1,7. In a fluid fuel control system: a main burner; a pilot burner; an electrically operated valve for the main burner; an electrically operated valve for the pilot burner; means, independent of the pilot burner valve, for temporarily passing fuel to the pilot burner; means responsive to the existence of the pilot flame for energizing the pilot burner valve; rectifler means connectible to a source of alternating current for supplying energy to said main burner valve; and means operating in response to the energization of the pilot burner valve for controlling said rectifier means to pass current to the main burner valve.

18. In a fluid fuel control system: a main burner; a pilot burner; an electrically operated valve for the main burner; an electrically operated valve for the pilot burner; means responsive to the existence of the pilot flame for energizing the pilot burner valve; manually operable means optionally to bypass said pilot burner valve; rectifier means connectible to a source of alternating current for supplying energy to said main burner valve; and means operating in response to the energization of the pilot burner current to the main burner valve.

19. In a fiuid fuel control system: a main burner; a pilot burner; an electrically operated valve for the main burner; an electrically operated valve for the pilot burner; a pair of rectifiers connectible to a source oi. alternating current; means for energizing one of said rectifiers to operate the pilot burner valve in response to the existence of thepilot flame; manually operable means optionally to bypass said pilot burner valve and means, operating in response to the passage of current through said one rectifier, for controlling the other rectifier to operate the main burner valve.

20. In a fiuid fuel control system; a main burner; a pilot burner; an electrically operated valve for the main burner; an electrically operated valve for the pilot burner; a pair 01' rectifiers. connectible to a source 01' alternating current; means for energizing one of said rectifiers to operate the pilot burner valve in response to the existence or the pilot flame; manually operable means optionally to bypass said pilot burner valve; means, operating in response to the passage of current through said one rectifier, for controlling the other rectifier to the main burner valve; and condition responsive means for activating said other rectifier.

WILLIAM A. RAY.

REFERENCES CITED The following references are of record in the file of this patent:

STATES PATENTS Number Name Date 1,809,280 Knowles June 9, 1931 1,880,871 Denison Oct. 4, 1932 2,274,384 Scanlan Feb. 24, 1942 2,290,776 Snyder July 21, 1942 2,304,641 Jones Dec. 8, 1942 2,408,954 Ray Oct. 8, 1945 

